A087621 (1,1) entry of powers of the orthogonal design shown below.

-1, 2, 4, -56, 80, -352, 64, 2176, -4864, 31232, -23552, -14336, 217088, -2056192, 2375680, -7307264, -4390912, 102367232, -169607168, 877133824, -397410304, -3042967552, 9265217536, -68308434944, 62495129600, -78483816448, -342993403904

Offset: 1

Author

Simone Severini, Oct 25 2003

Keywords

• easy
• sign

Comments

-1 +1 +1 -1 -1 +1 -1 -1

+1 +1 -1 -1 -1 -1 -1 +1

+1 +1 +1 +1 +1 +1 -1 +1

+1 -1 +1 -1 +1 -1 -1 -1

+1 -1 +1 -1 -1 +1 +1 +1

+1 +1 -1 -1 +1 +1 +1 -1

-1 +1 +1 -1 +1 -1 +1 +1

+1 +1 +1 +1 -1 -1 +1 -1

References

• S. Severini, A note on two integer sequences arising from the 3-dimensional hypercube, Technical Report, Department of Computer Science, University of Bristol, Bristol, UK (October 2003).

Links

• Index entries for linear recurrences with constant coefficients, signature (0,4,0,-64).

Formula

a(0)=1, a(1)=-1, a(2)=2, a(3)=4, a(n) = 4*a(n-2) - 64*a(n-4). - T. D. Noe, Dec 11 2006

G.f.: -x*(4*x+1)*(16*x^2-6*x+1)/(64*x^4-4*x^2+1). - Colin Barker, Aug 10 2012

Extensions

Corrected by T. D. Noe, Dec 11 2006